1. Field of the Invention
The invention relates to electrical devices and more specifically to electrical motors and generators coupled with Current Source Inverters (CSI) for use in electric motors and generators.
2. Description of the Related Art
The cost of a drive system for electric vehicles is currently very high. It is over four times the cost target for a year 2020 drive system. Permanent Magnets (PM) are a major cost driver in an interior PM machine. The cost of these and other PM machines, such as PM wind power generators, megawatt PM motors, depend on the supply and demand, and thus the commodity cost, of rare earth PM materials.
Voltage Source Inverters (VSIs) require bulky, expensive and temperature-limited DC bus capacitors. As operational temperatures increase, the ability of film capacitors to handle ripple currents decreases, necessitating the addition of even more capacitance.
The current, annual global vehicle production is around 70 million units. With this growing number of vehicles on the road and the pressure from global warming and non-renewable oil shortage, the on-line electric vehicles will help meet the market demand. The market for wind power generators is also growing rapidly. The integration of a U machine (e.g., electric motor with an uncluttered rotor architecture) and CSI can cut the cost and improve performance of wind power generators. The spin-off companies from this new technology would undoubtedly produce a strong positive impact on the economy.
Related background teachings, attributed to the present inventor, include U.S. patent application Ser. No. 12/466,169 Substantially Parallel Flux Uncluttered Rotor Machines filed May 14, 2009; U.S. Pat. No. 7,719,153 Permanent Magnet Machine and Method with Reluctance Poles and Non-identical PM Poles for High Density Operation; U.S. Pat. No. 7,550,890 High slot utilization systems for electric machines; U.S. Pat. No. 7,514,833 Axial gap permanent-magnet machine with reluctance poles and PM element covers; U.S. Pat. No. 7,518,278 High strength undiffused brushless machine and method; U.S. Pat. No. 7,270,203 Electric machine for hybrid motor vehicle; U.S. Pat. No. 7,129,611 Method and radial gap machine for high strength undiffused brushless operation; U.S. Pat. No. 7,023,171 Integrated inverter for driving multiple electric machines; U.S. Pat. No. 6,993,924 Floating loop system for cooling integrated motors and inverters using hot liquid refrigerant; U.S. Pat. No. 6,989,619 Rotor apparatus for high strength undiffused brushless electric machine; US Patent Application 20090236924 Brushless Machine With Tapered Poles; US Patent Application 20090146511 Permanent-Magnet-Less Synchronous Reluctance System; and US Patent Application 20070075604 High Slot Utilization Systems for Electric Machines, each of which is incorporated by reference in this application as if included in their entirety.
A Current Source Inverter (CSI) can eliminate a large portion of the capacitors but requires additional inductors. What is needed is the integration of an electric machine and an inverter.